1. Field of the Invention
The present invention relates to an X-ray computer tomography system equipped with two-dimensional arrays of X-ray detectors.
2. Description of the Related Art
A multi-slice X-ray computer tomography system is equipped with a detector in which a plurality of rows of detector elements are juxtaposed in the slice direction. A still improved, so-called two-dimensional array of detectors has appeared. In particular, plural detector modules are arrayed in the direction of channel. Each detector module consists of a matrix of semiconductor detector elements formed on a substrate.
In these X-ray detectors, contrivances are often made to shorten the apparent center-to-center distance (actual spatial resolution) between detector elements adjacent to each other in the direction of channel. One contrivance is to adopt an offsetting means for offsetting the center position of the detector relative to the slice centerline connecting the focal point of X-rays and the axis of rotation by a distance equal to a fraction of the channel pitch. Another is to adopt a zigzaggedly combtoothed collimator.
However, where the offsetting means is used, the apparent resolution can be improved only up to a half of the actual resolution. Even where the offsetting means is used in combination with the zigzaggedly combtoothed collimator, the apparent resolution can be improved only up to a quarter of the actual resolution. Where the zigzaggedly combtoothed collimator is adopted, the light reception efficiency decreases in inverse proportion to increase in the shielded area caused by the used collimator. In other words, the sensitivity is deteriorated.